188 



FLUORESCENCE OF THE URANYL SALTS. 



is approximately 77 units. If so, it is the shortest frequency interval 

 yet discovered in the fluorescence of the uranyl salts. 



A comparison of the location of the bands of the solid potassium 

 sulphate with those of the 1/15 normal solution shows that the bands 

 of the solutions are from 12 to 40 A.u. nearer the red, according to their 

 wave-lengths. 



URANYL POTASSIUM SULPHATE IN SULPHURIC ACID. 



The addition of sulphuric acid in moderate proportions to the 

 aqueous solutions of the potassium sulphate increases the intensity 

 and improves the resolution of the bands. 



A solution of the 5 c.c. of 4/15 normal aqueous solution to 1 c.c. of 

 acid was subjected to the cooling process. In figures 92 and 93 and 

 table 114 the shifts will be observed. Band 5, which is typical of the 

 other bands, shifted toward the violet by 21 A.u. at 120, and then 

 shifted 6 A.u. toward the red at 180. 



+ 20 

 



-60 



-120 



-180 



1400 



a 830C S400 5390 SI90 5370 J>0 1170 StIO 5180 S34 



FIG. 92. Uranyl potassium sulphate Temperature shift. 



(1) 1/15 normal, aqueous; (2) 1/150 normal, aqueous; (3) 1/1500 normal, aqueous; (4) 5 c.c. of 4/15 normal, 

 aqueous to 1 c.o. sulphuric acid; (5) 1 c.c. of 4/15 normal, aqueous to 1 c.c. sulphuric acid. 



The addition of acid in larger proportion 1 c.c. of acid to 1 c.c. of 

 4/15 normal solution resulted in a spectrum which shifted toward the 

 violet in a peculiar fashion with each decrement of temperature. (See 

 curve No. 5 of fig. 92.) The total shift of band 5 amounted to 42 A.u. 



Further dilution with acid, e. g., 20 c.c. of acid to 1 c.c. of solution, 

 resulted in another broad-banded spectrum at +20. With cooling, 

 however, partial resolution occurred. This is best observed in figure 

 94, where several narrow bands appear in the regions formerly occupied 

 by the broad bands. Homologous components are lettered a, 6, and c. 



Still greater dilution 50 c.c. of acid to 1 c.c. of aqueous solution 

 produced a spectrum which passed through the same development; 



